Long-clawed porcelain crab
The long-clawed porcelain crab is a small crustacean measuring less than half an inch (one centimeter) in length, characterized by its two long, thick claws. It belongs to the family Porcellanidae and is commonly found in the Northeastern Atlantic Ocean and the Mediterranean Sea. Typically residing under stones and among seaweed in shallow waters, this crab may inhabit the shells of dead oysters or live alongside other marine creatures, such as hermit crabs and various sponges. Its reddish-brown carapace, which resembles a turtle shell, serves as a protective exoskeleton, essential for safeguarding its soft body from predators and moisture loss.
The crab has a three-part body structure, including a small head with antennae and eyes, a larger thorax housing its gills and legs, and a distinct abdomen. With a total of ten legs, some are adapted for walking and swimming while others are smaller and less functional. The long-clawed porcelain crab feeds by filtering particles from the water and undergoes a molting process to grow, shedding its old carapace for a new one. Reproduction involves males fertilizing females while their carapace is still soft, after which females carry fertilized eggs until they hatch into free-swimming larvae. The life span of this intriguing species remains unknown.
Subject Terms
Long-clawed porcelain crab
This crab's body is less than 1/2 inch (one centimeter) long, and has two long, thick claws. Its small size may enable it to live in the shells of dead oysters or to live inside the homes of other living animals, such as hermit crabs, sponges, ragworms, and lugworms.
Kingdom: Animalia
Phylum: Crustacea
Class: Malacostraca
Order: Decapoda
Family: Porcellanidae
Genus: Porcellana
Species: Longicornis
The long-clawed porcelain crab makes it home under the stones and among the seaweed along the shore and in shallow waters. Because of its small size it is possible that it may live inside the shells of dead oysters, either by itself or with other crabs of its species. Other homes may possibly be in the shells of living hermit crabs or other ocean-dwelling animals, such as the tubes of ragworms and lugworms or among various types of sponges. The range of the long-clawed porcelain crab extends throughout the Northeastern Atlantic Ocean and the Mediterranean Sea.
The reddish-brown carapace of this crab is broad and flat. A carapace is the hard shell which covers the head and body of this and other crab species. The carapace of the long-clawed porcelain crab is similar to the carapace of a turtle. The carapace is made of a hard material which the crab's body secretes. Plates of this same hard material also cover the legs and claws of the crab. The carapace forms the exoskeleton, or external skeleton, of the crab since it does not have bones inside its body. This hard shell is important in protecting the soft body of the crab from predators and from death by losing body moisture.
The body of the long-clawed porcelain crab has three parts. The head is small but has two long antennae for detecting food and sensing surroundings. It also has two eyes on little stalks which the crab can extend or withdraw. Behind the head is the thorax, or mid-body section, which is the largest part of the crab. The legs are located on the sides of this section. On the bottom of the thorax are also the nine pairs of gills used for breathing. Behind the thorax is the abdomen, or tail section. It has distinct markings on it. The overall length of the long-clawed porcelain crab is less than 1/2 inch (one centimeter).
Like all other decapods, the long-clawed porcelain crab has 10 legs. These extend from the sides of its rounded or oval-shaped body. Three of these pairs of legs are for walking and swimming. The last pair of legs on the body are small and probably are not used much. The fifth pair of legs is located just behind the head. Each of these two legs has a long claw on the tip. The claws have teeth along their edges. The crab filters particles of food from the water.
Each year an adult male or female crab molts, or sheds, its carapace to make room for a new, larger carapace which has formed underneath the old one. The new carapace is soft at first but hardens within a few days. The male likely mates with the female while her carapace is still soft. The male's sperm fertilizes the female's eggs, and she then probably carries the eggs on the underside of her abdomen until they hatch a couple weeks later. The young probably are zoeae larvae at first. These larvae swim freely in the water for a short time, during which they molt, or shed, their skins several times and begin to look more like crabs. They are then called megalops larvae and have big eyes. Soon they settle to the bottom and become adult crabs.
The life span of the long-clawed porcelain crab is not known.